German patent application No. 40 32 797 discloses a hydraulic automotive vehicle brake system with wheel slip control which has a pump and pressure modulation valves in the brake line to control the wheel braking pressure. The pump piston is directly acted upon by the pressure of the braking pressure generator so that the full pressure of the braking pressure generator is applied to the sealing of the pump piston. In defined cases of application, especially for operation of the pump for driving dynamics control purposes, particularly high demands are placed on the above-mentioned sealing of the pump piston in order to ensure in any case a reliable sealing of the crank chamber which is usually subjected to atmospheric pressure.
For automotive vehicle brake systems equipped with a driving dynamics control system, it is preferred to use a type of pump as disclosed in German patent application No. 32 36 536. This type of pump is characterized by a central suction channel arrangement in the pump piston. Therefore, considerable requirements are imposed on the sealing of the pump piston in relation to the eccentric chamber with a pump of this type.
An object of the present invention is to improve upon a hydraulic automotive vehicle brake system of the above-mentioned type to such effect that leakage flow via the pump piston in the direction of the eccentric chamber is prevented by least possible efforts in terms of structure and function.
According to the present invention, this object is achieved by the features characterizing patent claim 1.
Further features and advantages of the present invention can be seen in the subclaims which refer to features related to structure and circuit technique for the configuration of restrictors.